Self-regulating fluid pressure operated power cylinder



Sept. 13, 1960 S. REIS SELF-REGULATING FLUID PRESSURE OPERATED POWERCYLINDER /5 I 4 I ,2 25* F f I .15 (24 9/72 10 7 2.5 86 80 C 1 v 7 F 110 *TTgJ5 3 Filed NOV. 22, 1957 INVENTOR.

United States Patent SELF-REGULATING FLUID PRESSURE OPER- ATED POWERCYLINDER Smil Reis, Via Mauro Macchi63, Milan, Italy Filed Nov. '22,1957, Ser. No. 698,255 Claims priority, application Italy Dec. 6, 1956 2Claims. or. 131-115 This invention relates to a fluid pressure operatedpower cylinder adapted to open and close automatically the supply of theoperating fluid, when its pressure reaches a pre-set upper, respectivelylower limit, thus relieving the source of fluid pressure from load, atthe upper limit.

This invention may also be used in any fluid pressure operated powersystem, for maintaining the fluid pressure between pre-set limits. Itprovides a very simplified construction, which operates with eifectiveprecision in response to exact pressure limits, and avoids any conditionthat may cause to any components, what is commonly known as chattering.

The objects, advantages and aims of this: invention, will appearsubstantially, from the description given below with reference to oneembodiment and its operation, shown schematically in the accompanyingdrawing wherein Fig. 1 shows a sectional view taken axially through thepower cylinder; Fig. 2 shows the power cylinder with its components inone operative position; 'Fig. 3 shows the power cylinder with itscomponents in a second operative posit-ion; and Fig. 4 shows the powercylinder in an arrangement for operating a power user.

With reference to the Fig. l, the cylinder body 1 has a closed upperend, a lateral inlet port 2, and a lateral outlet port 3. The inlet port2 is situated between the outlet 3 and the closed end of the cylinder 1.A second outlet port '4, is situated at the closed end of said cylinder1.

In the bore 5 of the cylinder 1 is arranged slidably, a compound piston6-8 having a first upper part 6 with a stem 7, and a second lower part 8axially slidable thereon Said lower part 8 is kept at a certain distancefrom said upper part 6, urged by a spring against a retainer 9 fixed tosaid stem 7. Said spring 10 is arranged between said parts 6 and 8, inan intermediate portion of their length, said intermediate portion beingrecessed to form a first chamber 11.

The upper part 6 is shaped so as to form in co-operation with the closedend of the cylinder 1, a second pressure chamber 12.

The first chamber 11 is in permanent communication with the inlet 2,while the pressure chamber 12 is permanently communicating with theoutlet 4. A duct 13 in said upper part 6 connects the chambers 11 and12, and a valve 14, loaded by a spring 15, controls the passage throughsaid duct 13, so that fluid can flow from chamber 11 into chamber 12,but not inversely.

A spring 16, arranged between the retainer 9 and a second retainer 17fixed to the open end of the cylinder 1, urges said compound piston 6-8upwards to the inner end of its stroke. At this position, the lower part8 closes the outlet 3.

A second bore 18 with a second piston 19 therein, is situated at theopen end of the cylinder 1, perpendicularly to the main bore 5. A plug20 fixed to the second piston 19, projects through a hole of thecylinder wall, into the main bore 5, and is adapted to stop the lowerpart spring 26. The plug 20 fits the hole through which it projects intothe main bore 5, so that fluid from the restricted portion 22 cannotpass into said main bore 5. The restricted portion 22 is communicatingthrough a duct 23and a port 24, with the first chamber 11, and

' through said duct 23 and a second port 25, with the chamber 12. Theport 25 is situated so that it remains normally closed by the upper part6 of the compound piston 68, and is opened when said part reaches theouter end of its stroke, while the port 24 is situated so that it isclosed by the same part 6, before the port 25 is opened.

When the invention is to be used as a power cylinder, a cook 27, (Fig.4); or any known device adapted to open and close the outflow fromchamber 12, will be fitted to the outlet port 4, and the power will betransmitted to the power user not shown, through the piston stem 7, towhich said power user will have to be connected. In this case, thecylinder will work under load, when the outlet 4 will be closed.

For use to maintain pressure between pre-set limits in a fluid pressureoperated system, the pressure pipe (not shown) through which pressurefluid is supplied to said system will have to be connected to saidoutlet 4.

The fluid supplied through the inlet port 2 reaches the pressure chamber12 through the first chamber 11, the duct 13 and the valve 14, thelatter being forced to open, by the same pressure fluid. With the outlet4 opened, there is no rise in pressure more t-hannecessary to keep thevalve 14 open and to overcome the resistance to flow. When the outlet 4is closed, the pressure in chamber 12 rises and the compound piston 68moves as one solid piece, downwards to the open end of the cylinder 1,until the lower edge of its lower part 8 will be stopped by the plug 20.The pressure will continue to rise until the tension of the spring 10 isovercome. At this point, while the lower part 8 is withheld by the plug20, the upper part 6 continues to move downwards, closing first the port24 (-Fig. 2) and opening successively the port 25 (Fig. 2 and Fig. 3).

Pressure is now admitted within the restricted portion 22 of the bore18, urging the piston 19 to withdraw the plug 20, so that the spring 10,whose tension, properly selected, is higher than that of the spring 16,will force rapidly the lower part 8 of the compound piston 6-8,downwards to the outer end of its stroke, thus opening the outlet 3. Thepressure within the first chamber 11, and thus also that of the sourcethat supplies it, is therefore relieved, while the pressure in chamber12 remains maintained, the valve 14 closing the passage back to the duct13.

When the outlet '4 is opened, or the pressure in the pressure pipe to itconnected, drops below a limit depending upon the tension of the spring16, the compound piston 6-8 is urged again upwards to the inner end ofits stroke, closing. the outlet 3 and the port 25, and opening the port24, through which also the second piston 19 and the restricted portion22 of the bore 18, will be the upper pressure limit setting may beregulated from outside, by means of any well known arrangement adaptedfor this purpose.

It will further be remarked that there is no possibility for chatteringof "any of the .movable components of this invention, because thereisnone that can remain in an uncertain condition, wherein the opening ora fluid passage has been started, but cannot be completed.

I claim:

1. A self regulating 'fiuid pressure-operated power'cylinder comprisinga cylinder body with a cylinder bore, a first upper piston part thereinand a stem fixed theretotfor transmitting the piston power to any poweruser outside said power cylinder, :21 second lower piston part carriedslidable on said stem, a spring between said piston parts urging thelower piston .part against a retainer of said stem apart from the upperpiston part, a recessed portion between said upper and lower piston partforming a first chamber in said cylinder bore, an inlet port openingpermanently into said first chamber for continuously ad mitting pressurefluid therein, a relief outlet located along the cylinder bore so as tobe fully opened into said first chamber by the lower piston part whensaid lower piston part is at the outer end of its stroke, a secondchamber pressure fluid from the first into the second chamber but notinversely, resilient .means urging the stem and the upper piston part tothe inner end of its stroke, withdrawable springloaded means to stop thelower piston part along the piston stroke at a position just before therelief outlet begins to open and fluid pressure operated means forwithdrawing :said springloaded means so that the lower piston part canbe freely displaced to the outer end of its stroke by its expandingspring, thus opening fully said relief outlet.

2. A self regulating fluid pressure operated power cylinder as in claim1, including a duct for transmitting fluid pressure to actuate thewithdrawing means, a port connecting said duct-to the first chamber andanother port for the fluid under pressure formed between the upperpiston part and the upper closed end of the cylinder bore, an outletport of said second chamber for the egress of said fluid under pressuretherefrom, the upper piston part separating said first from said secondchamber, a duct and a valve between said chambers for admittingconnecting said duct to the second chamber, the said other port beingkept normally closed by the upper piston part and located along thecylinder bore so that it is uncovered when said upper piston partreaches the outer end of its stroke, and the said port being normallyopen and located so that it is closed by the upper piston part justbefore said other port is uncovered.

References Cited in the file of this patent UNITED STATES PATENTS2,732,851 Ashley et :al Jan. 31, 1956 2,733,727 Trevaskis Feb. 7, 1956FOREIGN PATENTS 519,429 Great Britain Mar. 27, 1940

